Method for efficient data transformation

ABSTRACT

A digraph including a plurality of ordinary nodes, at least one of a composition node and a decomposition node, and a plurality of arcs interconnecting any of said nodes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of and claimspriorify benefit from U.S. patent application Ser. No. 10/211,171, nowU.S. Pat. No. 7,356,480, filed on Aug. 1, 2002.

FIELD OF THE INVENTION

The present invention relates to data transformation.

BACKGROUND OF THE INVENTION

In today's business environment, many applications and solutions need touse data that are expressed in different formats and languages.Effective use of data often requires that data be transformed from onedata format into another.

For example, healthcare providers, such as physicians, create largevolumes of patient information at healthcare facilities, such ashospitals, clinics, laboratories, and medical offices. Often, a patientmay be treated by more than one healthcare provider, necessitating thatthe patient's records at one healthcare provider be readily available toother healthcare providers, as this information might be critical to thehealthcare provider when treating the patient. Unfortunately, the widevariety of formats in which information is stored might impede thehealthcare provider's ability to assimilate the information. Althoughmedical data may be converted from one format to another to facilitatedata interchange and thereby potentially improve patient care, doing soefficiently and at a minimum cost is vital in light of spiraling medicalcosts.

In many cases, transformation of data from a source format into a targetformat is carried out as a series of transformations to one or moreintermediate data formats. While transformations might also be requiredthat unify multiple data formats (i.e., many-to-one cardinality), thatresult in several target formats (i.e., one-to-many cardinality), orboth (i.e., many-to-many cardinality), techniques for determining themost efficient paths for transformations of various cardinalities do notcurrently exist.

SUMMARY OF THE INVENTION

The present invention discloses a method for efficient datatransformation, particularly where multiple transformation paths areavailable and where transformations may be one-to-one, one-to-many,many-to-one, or many-to-many. The present invention facilitatesefficient data transformation and interchange in fields such as, but notlimited to, medical records management, multimedia production, andbusiness data warehousing.

In the present invention, a table of data transformations and theirassociated costs are expressed in a single digraph, where source andtarget data formats are represented as nodes connected by cost-labeledarcs. Each arc connecting the nodes has a nonnegative cost, where thecost may be expressed in terms of transformation execution time, laborcosts, or any other costs. The most efficient transformation paths fromthe sources to the targets are then determined as those transformationpaths that incur the lowest accumulated cost.

In one aspect of the present invention a digraph is provided including aplurality of ordinary nodes, at least one of a composition node and, adecomposition node, and a plurality of arcs interconnecting any of thenodes.

In another aspect of the present invention the composition node isconnected to at least two of the nodes via arcs incoming to thecomposition node and to one other of the nodes via an arc outgoing tothe other node.

In another aspect of the present invention the decomposition node isconnected to one of the nodes via an arc incoming to the compositionnode and to at least two other of the nodes via arcs outgoing to theother nodes.

In another aspect of the present invention the ordinary nodes representdata formats.

In another aspect of the present invention a first one of the ordinarynodes connected via an outgoing one of the arcs to a second one of theordinary nodes represents a transformation of one data format intoanother.

In another aspect of the present invention any of the arcs has anassociated non-negative cost.

In another aspect of the present invention a method is provided forconstructing a digraph from a plurality of source-to-target traversals,the method including representing the sources and targets as a pluralityof ordinary nodes, representing any of the traversals having aone-to-one cardinality by connecting the source node of the traversal tothe target node of the traversal by an arc outgoing from the sourcenode, and performing any of the following representing any of thetraversals having a many-to-one cardinality by connecting the sourcenodes of the traversal to a composition node by arcs outgoing from thesource nodes, and by connecting the composition node to the target nodeof the traversal by an arc outgoing from the composition node,representing any of the traversals having a one-to-many cardinality byconnecting the source node of the traversal to a decomposition node byan arc outgoing from the source node, and by connecting thedecomposition node to the target nodes of the traversal by arcs outgoingfrom the decomposition node, and representing any of the traversalshaving a many-to-many cardinality by connecting the source nodes of thetraversal to a composition node by arcs outgoing from the source nodes,by connecting the composition node to a decomposition node by an arcoutgoing from the composition node, and by connecting the decompositionnode to the target nodes of the traversal by arcs outgoing from thedecomposition node.

In another aspect of the present invention the method further includesassociating a non-negative cost with any of the arcs.

In another aspect of the present invention a method is provided ofefficient path discovery in a digraph including a plurality of ordinarynodes, at least one of a composition node and a decomposition node, anda plurality of arcs interconnecting any of the nodes, the methodincluding providing a source node s connected to a set S of source nodesin the digraph via outgoing arcs of zero cost, initializing to zero acumulative cost of the path to s, providing a composition node t′connected to a set T of target nodes in the digraph via incoming arcs ofzero cost, providing a target node t connected to composition node t′via an incoming arc of zero cost, defining a set W of nodes in thedigraph initially including only node s, defining a set V of all nodesin the digraph, determining the cumulative costs of the paths to allnodes y in V that are connected to node s by an arc, while W<>Vselecting a node x in V from all nodes in V that are not in W whosecumulative cost is minimal, adding node x to W, and for each node y in Vto which x has an outgoing arc if y is not a composition node,determining the cumulative cost of the path to y as the lesser of a) thecurrent known cumulative cost of the path to y, and b) the cumulativecost of the path to x plus the cost of the arc connecting x to y, if yis a composition node, and all nodes that have outgoing arcs to y are inW, determining the cumulative cost of the path to y as the lesser of a)the current known cumulative cost of the path to y, and b) the sum ofthe cumulative costs of the paths to all nodes that have outgoing arcsto y.

In another aspect of the present invention the method further includesdetermining the most efficient path from node s to a destination nodeselected from any of the nodes as including the arcs whose cost wasadded to the final cumulative cost of the destination node.

In another aspect of the present invention the method further includesdetermining the most efficient path from S to T as including the arcswhose cost was added to the final cumulative costs of the nodes of T.

In another aspect of the present invention the step of determining themost efficient path includes a) traversing each incoming arc of eachnode in T whose cost was added to the final cumulative cost of eachcurrent node, to arrive at one or more next nodes in the path, b)traversing each incoming arc of each node arrived at in the previousstep whose cost was added to the final cumulative cost of each nodearrived at in the previous step, to arrive at one or more next nodes inthe path, and c) repeating step b) until the currently-arrived-at nodesare the nodes of S, where the traversed arcs together form the mostefficient path from S to T.

In another aspect of the present invention a computer program isprovided embodied on a computer-readable medium, the computer programincluding a first code segment operative to provide a source node sconnected to a set S of source nodes in a digraph via outgoing arcs ofzero cost, the digraph including a plurality of ordinary nodes, at leastone of a composition node and a decomposition node, and a plurality ofarcs interconnecting any of the nodes, a second code segment operativeto initialize to zero a cumulative cost of the path to s, a third codesegment operative to provide a composition node t connected to a set Tof target nodes in the digraph via incoming arcs of zero cost, a fourthcode segment operative to provide a target node t connected tocomposition node t′ via an incoming arc of zero cost, a fifth codesegment operative to define a set W of nodes in the digraph initiallyincluding only node s, a sixth code segment operative to define a set Vof all nodes in the digraph, a seventh code segment operative todetermine the cumulative costs of the paths to all nodes y in V that areconnected to node s by an arc, an eighth code segment operative, whileW<>V, to select a node x in V from all nodes in V that are not in Wwhose cumulative cost is minimal, add node x to W, and for each node yin V to which x has an outgoing arc if y is not a composition node,determine the cumulative cost of the path to y as the lesser of a) thecurrent known cumulative cost of the path to y, and b) the cumulativecost of the path to x plus the cost of the arc connecting x to y, if yis a composition node, and all nodes that have outgoing arcs to y are inW, determine the cumulative cost of the path to y as the lesser of a)the current known cumulative cost of the path to y, and b) the sum ofthe cumulative costs of the paths to all nodes that have outgoing arcsto y.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with theappended drawings in which:

FIGS. 1A, 1B, 1C, and 1D are simplified illustrations of digraphelements, constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 2, which is a simplified illustration of a digraph, constructed andoperative in accordance with a preferred embodiment of the presentinvention;

FIGS. 3A and 3B, taken together, is a simplified flowchart illustrationof a method of efficient path discovery in a digraph, operative inaccordance with a preferred embodiment of the present invention;

FIGS. 4A, 4B, 4C, and 4D are simplified illustrations of the digraph ofFIG. 2 reflecting the application of the method of FIGS. 3A and 3B.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIGS. 1A, 1B, 1C, and 1D, which are simplifiedillustrations of digraph elements, constructed and operative inaccordance with a preferred embodiment of the present invention. Inaccordance with the present invention, a digraph is constructed torepresent one or more source-to-target traversals, such as atransformation of data from a source format into a target format, andtheir attendant costs. If a transformation t has a cost=1, a cardinalityof one-to-one, and transforms data from format {a1} to format {b1}, thesub-graph of FIG. 1A is created, where {a1} and {b1} are represented bynodes 10 interconnected by an arc 12 whose direction indicates thelogical direction of the transformation. If t has a cost=1, acardinality of one-to-many, and transforms data from format {a1} toformats {b1,b2}, the sub-graph of FIG. 1B is created. The one-to-manycardinality is represented by a square-shaped decomposition node 14. Ift has a cost=1, a cardinality of many-to-one, and transforms data fromformats {a1,a2} to format {b1}, the sub-graph of FIG. 1C is created. Themany-to-one cardinality is represented by a plus-shaped composition node16. The composition node of the present invention requires thattransformation t may be executed only after all data in source formats{a1,a2} exist. If t has a cost=1, a cardinality of many-to-many, andtransforms data from formats {a1,a2,a3} to formats {b1,b2}, thesub-graph of FIG. 1D is created, combining the sub-graphs of FIGS. 1Band 1C. For the sake of clarity, a node that is neither a compositionnode nor a decomposition node is herein referred to as an ordinary node.

Reference is now made to FIG. 2, which is a simplified illustration of adigraph, constructed and operative in accordance with a preferredembodiment of the present invention. The digraph of FIG. 2 is anexemplary construction using the sub-graphs of FIGS. 1A 1D which modelsa number of transformations, shown in Table A, from source data formats,such as flat file and database (db), into target data formats, such asrtfXm1 and dbXm1 respectively. Each transformation is associated with acost, which may represent any non-negative relevant cost, such asprocessing time, memory used, number of computer operations, etc.

TABLE A Sources Targets Cost flatFile rtfXml 1 db dbXml 3 db 123 1wordpro html 2 123 html 0.5 123 dbXml 1 rtfXml, dbXml performanceML 1html, dbXml performanceML 1 rtfXml, dbXml XHTML 2 html text, gif 2

It will be seen in Table A that some transformations may requiremultiple sources, such as the transformation of rtfXm1 and dbXm1 intoperformanceML, and that some transformations split a single source intomultiple target formats, such as the transformation of html into textand gif.

For both diagrammatic clarity and generality of description, each sourceand target of Table A may be expressed as numbered nodes, such as isshown in Table B as follows:

TABLE B Source Nodes Target Nodes Cost 102 116 1 104 118 3 104 120 1 106122 2 120 122 0.5 120 118 1 116, 118 110 1 122, 118 110 1 116, 118 108 2122 112, 114 2

The digraph of FIG. 2 is constructed to represent the collection ofsource nodes and target nodes, where each transformation is depicted,using the sub-graphs of FIGS. 1A 1D, as a set of arcs and nodes, whereeach arc is shown together with its associated cost.

Source node 104 is shown connected both to node 118 and to node 120.This type of digraph notation may be used to represent, for example,that a single source data format may be transformed into either of twodifferent data formats, represented by node 118 and node 120respectively. The arc from node 120 to node 118 may also be used to showthat the source data format represented by source node 104 may betransformed into the data format represented by node 118, first viatransformation into the data format represented by node 120, and thenvia transformation into the data format represented by node 118.

Many-to-one cardinality, such as where data in two or more data formatsare to be combined into a single data format, is shown represented byplus-shaped composition nodes 124, 126, and 128, whose incoming arcs areassigned a zero cost. One-to-many cardinality, such as where one dataformat is to be split into or otherwise transformed into two or moredifferent data formats, is shown represented by a square-shapeddecomposition node 130. The outgoing arcs from decomposition nodes arealso assigned a zero cost.

The constructed digraph of the present invention may be used as thebasis for formulating a query whose purpose is to determine the mostefficient path between any two nodes or between any two groups of nodes,where efficiency is defined as the lowest cumulative cost of the arcsalong a given path. The decision whether to traverse a particular arcmay be made by considering the cumulative cost of the arcs traversed andselecting the path having the lowest cumulative cost. A preferred methodof efficient path discovery in the digraph of the present invention isnow described.

Reference is now made to FIGS. 3A and 3B, which, taken together, is asimplified flowchart illustration of a method of efficient pathdiscovery in a digraph, operative in accordance with a preferredembodiment of the present invention. In the method of FIGS. 3A and 3B,given a set S of source nodes, a set T of target nodes, and variouspaths therebetween, a single source node s is introduced into thedigraph and connected via outgoing arcs of zero cost to each of thesource nodes S. A cumulative cost of the path to s is typicallyinitialized to zero, since s is the node of origin for all source nodes.A single composition node t′ is also defined and connected via incomingarcs of zero cost to each of the target nodes T. A single target node tis likewise defined and connected via an incoming arc of zero cost tothe composition node t′.

A set W of nodes is defined and initially includes only node s. A set Vis likewise defined including all nodes in the digraph. The cumulativecost of the path from s to any given node in V is initially unknown, andis, therefore, typically considered to be infinite. The following stepsare then performed to find the cumulative cost from s to any node in V:

1) The cumulative costs of the paths to all nodes y in V that areconnected to node s by an arc are determined by the cost of the arc.

2) While W<>W:

3) A node x in V is selected among all nodes in V that are not in Wwhose cumulative cost is minimal. If there is more than one minimalnode, then any node x may be selected.

4) Node x is added to W.

5) For each node y in V to which x has an outgoing arc:

6) If y is not a composition node, then the cumulative cost of the pathto y is the lesser of a) the current cumulative cost of the path to y,if known, and b) the cumulative cost of the path to x plus the cost ofthe arc connecting x to y;

7) If y is a composition node, and all nodes that have outgoing arcs toy are in W, then the cumulative cost of the path to y is the lesser ofa) the current cumulative cost of the path to y, if known, and b) thesum of the cumulative costs of the paths to all nodes that have outgoingarcs toy.

The most efficient path from node s to any other destination node, andultimately to node t, is comprised of the arcs whose cost was added tothe final cumulative cost of the destination node. From this, it may beseen that the most efficient path from S to T may be derived as follows:

a) traverse each incoming arc of each node in T whose cost was added tothe final cumulative cost of each current node, to arrive at one or morenext nodes in the path;

b) traverse each incoming arc of each node arrived at in the previousstep whose cost was added to the final cumulative cost of each nodearrived at in the previous step, to arrive at one or more next nodes inthe path;

c) repeat step b) until the currently-arrived-at nodes are the nodes ofS. The traversed arcs together form the most efficient path from S to T

It may thus be seen that the method of FIGS. 3A and 3B may be used as amethod of efficient data transformation when applied to a datatransformation table such as Table A hereinabove.

The method of FIGS. 3A and 3B may be alternatively understood using thefollowing pseudocode:

Input: A digraph D = (V, A), with costs Cuv >= 0 on its arcs, and Vhaving >= 0 composition nodes and >= 0 decomposition nodes. A set ofsources nodes S such that each node in S belongs to V. Output: Thelowest-cost paths from S to all nodes in V in an array p. Begin:Construct a new node, s, and add arcs with cost = 0 from s to every nodein S. Construct a new node, t, and a new composition node t′. Add arcswith cost = 0 from all the nodes in T to the composition node, t′, andfrom the composition node to t. Add all the new nodes and arcs to thedigraph D=(V,A). Set W := {s}; p[s] := 0 ; for all y such that y is anode in V with an incoming arc from s do p[y] := Csy ; while W <> V dobegin   find min {p[y] : y is not in W} , say p[x];   set W := W union{x} ;   for all y in V such that there is an arc from x to y do   begin    if y is not a composition node then       p[y] := min {p[y] , p[x] +Cxy}     else if all nodes that have outgoing arcs to y are in W then      p[y] := min {p[y] ,sum of all p[z] where z has an         outgoingarc to y}   end end end

Thus, by applying the method of FIGS. 3A and 3B, the most efficient pathfrom s to t is determined as those arcs whose cost was added to thefinal cumulative cost of t. From this, the most efficient path from S toT may be derived as described hereinabove.

Reference is now made to FIGS. 4A, 4B, 4C, and 4D which show the digraphof FIG. 2 reflecting the application of the method of FIGS. 3A and 3B toan exemplary query in which the most efficient path is determined forthe transformation of the set of source nodes 102, 104, and 106 into theset of target nodes 108 and 110. FIG. 4A shows the digraph of FIG. 2 forwhich s, t′, and t have been defined. In FIG. 4B the arcs shown indashed lines represent those arcs that lay along the most efficientpaths from s to any node in V, and in particular to t. In FIG. 4C thearcs shown in dashed lines represent those arcs that do not lay alongany efficient path and are the complementary arcs to those in FIG. 4B.Finally, in FIG. 4D the arcs shown in dashed lines represent those arcsthat lay along the most efficient paths from source nodes 102, 104, and106 to target nodes 108 and 110, being a subset of the arcs shown inFIG. 4B.

It is appreciated that one or more of the steps of any of the methodsdescribed herein may be omitted or carried out in a different order thanthat shown, without departing from the true spirit and scope of theinvention.

While the methods and apparatus disclosed herein may or may not havebeen described with reference to specific hardware or software, it isappreciated that the methods and apparatus described herein may bereadily implemented in hardware or software using conventionaltechniques.

While the present invention has been described with reference to one ormore specific embodiments, the description is intended to beillustrative of the invention as a whole and is not to be construed aslimiting the invention to the embodiments shown. It is appreciated thatvarious modifications may occur to those skilled in the art that, whilenot specifically shown herein, are nevertheless within the true spiritand scope of the invention.

1. A method for constructing a digraph from a plurality ofsource-to-target traversals, the method comprising: representing in agraph a one-to-many transformation of electronic data from a source dataformat into a plurality of target data formats, wherein said one-to-manytransformation is represented in said graph by a node representing saidsource data format, a plurality of nodes representing said target dataformats, and a node that is identified as a decomposition noderepresenting a one-to-many transformation, wherein said noderepresenting said source data format is connected to said decompositionnode by an arc having an associated non-zero cost representing a cost ofsaid one-to-many transformation, and wherein said decomposition node isconnected to said plurality of nodes representing said target dataformats by a corresponding plurality of arcs having an associated zerocost per arc; representing in said graph a many-to-one transformation ofelectronic data from a plurality of source data formats into a targetdata format, wherein said many-to-one transformation is represented insaid graph by a plurality of nodes representing said source dataformats, a node representing said target data format, and a node that isidentified as a composition node representing a many-to-onetransformation, wherein said plurality of nodes representing said sourcedata formats are connected to said composition node by a correspondingplurality of arcs having an associated zero cost per arc, wherein saidcomposition node is connected to said node representing said target dataformat by an arc having an associated non-zero cost representing a costof said many-to-one transformation and that is traversable only afterall of said arcs from said source data formats to said composition nodeare traversed, and wherein said nodes representing said source dataformats and said nodes representing said target data formats areidentifiably distinguishable from said composition node and saiddecomposition node, wherein said composition node is identifiablydistinguishable from said decomposition node, and wherein saidrepresenting steps are embodied in any of a) computer hardware, and b)computer software embodied in a non-transitory, computer-readablemedium.
 2. A method according to claim 1 and further comprisingassociating a non-negative cost with any of said arcs.
 3. A methodaccording to claim 1 and further comprising representing in said graph amany-to-many transformation of electronic data from said plurality ofsource data format nodes connected to said composition node into saidplurality of target data format nodes connected to said decompositionnode by connecting said composition node to said decomposition node byan arc outgoing from said composition node to said decomposition nodeand having an associated non-zero cost representing a cost of saidmany-to-many transformation and that is traversable only after all ofsaid arcs from said source data formats to said composition node aretraversed.